A storage region providing device configured to provide a physical region that is a physical storage region of a storage device as a logical region that is a virtual storage region is known. As one of storage region providing devices of this type, a storage region providing device described in Patent Document 1 accepts a writing request. The writing request includes data and partial logical region specification information for specifying a partial logical region that is part of a logical region.
In a case that part of the physical region is not allocated yet to the partial logical region specified by the partial logical region specification information included in the writing request, the storage region providing device allocates part of the physical region (a partial physical region) to the partial logical region. Then, the storage region providing device stores the data into the partial physical region allocated to the partial logical region.
Thus, the storage region providing device allocates a partial physical region to a partial logical region (i.e., secures a physical region for a partial logical region) for the first time at a moment of actually storing (writing) data. Consequently, it is possible to prevent wasteful securing of a physical region that is not used actually. This function is called a thin provisioning (or a virtual provisioning) function.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. JP-A 2010-86420
Every time accepting a writing request, the storage region providing device searches for a region that is not used (not allocated to any logical region) (an unallocated region) in the physical region, for example, from the beginning of the physical region, and allocates an unallocated region that is searched for at first to a partial logical region specified by the writing request.
A case in which partial logical regions composed of partial logical regions specified by partial logical region specification information included in a plurality of writing requests, respectively, are continuously located in the logical region (e.g., a case in which data configuring one file are stored by a plurality of writing requests) will be assumed. In this case, according to the storage region providing device described above, a state in which partial physical regions allocated to the partial logical regions are separately located in the physical region will be caused.
Thus, there is a fear that the speed of accessing the data stored in the storage device (e.g., retrieving the data configuring the file, changing the data configuring the file) excessively decreases.